While routine physical activity is critical to optimal health, residents of low-income Los Angeles communities are less likely to exercise than those in high-income communities, and they are less likely to use their neighborhood parks, even when the parks are within walking distance. Parks in low-income neighborhoods tend to be smaller and serve a greater population density, but even after accounting for the size and population served, they are still used less than parks in wealthier neighborhoods. In our preliminary studies we found that parks in low-income neighborhoods also had fewer part-time staff and offered fewer programs and organized activities than parks in higher-income areas, and these factors accounted for their lower use. Parks in low-income neighborhoods are often perceived as less safe, a characteristic associated with lower use. Simultaneously, the lack of use and dearth of programming may contribute to a perception of lack of safety, creating a vicious cycle. Nonetheless, we have documented that when parks in low-income neighborhoods offer events and activities, they can be just as busy as parks in higher-income areas. We hypothesize that limited park use in low- income areas can be attributed to the lack of organized and reliable infrastructure of activities that meet the needs of local residents, an infrastructure that is more reliable and often taken for granted in higher income neighborhoods. The proposed study has three specific aims: 1) Using a full factorial design, compare whether park use and population physical activity in low-income neighborhoods increase with the availability of a) more organized physical activity classes, including zumba, line dancing, and aerobics indoors and outdoors and/or b) a loyalty program approach that rewards frequent park users. 2) Determine whether either of these two approaches changes the perception of park safety and neighborhood safety. 3) Identify the cost effectiveness of both approaches in terms of dollars spent to generate increased physical activity in parks as measured through systematic observation. Our study will document all the steps required for implementing and maintaining two physical activity promotion interventions-- one a standard approach offering traditional organized physical activity programs, the other an innovative application of popular customer loyalty programs. We will determine their impact on physical activity and their cost-effectiveness.